SSTS_DREG_FULL
while (hd->scsi_ssts & SSTS_DREG_FULL) {
while (hd->scsi_ssts & SSTS_DREG_FULL) {
while ((bus_space_read_1(iot, ioh, SSTS) & SSTS_DREG_FULL) != 0)
if ((sstat & SSTS_DREG_FULL) != 0) {